Vancomycin kinetics in plasma and synovial fluid following intravenous administration in horses.

This research investigated how the drug Vancomycin, when given to horses intravenously, affects the plasma and synovial fluid. The study established a protocol for vancomycin administration by modeling the pharmacokinetics, measuring the antibiotic’s minimum inhibitory concentration and minimal bacterial concentration against Staphylococcus aureus and Enterococcus species.

Research Methodology

• The study involved administering Vancomycin hydrochloride intravenously to five horses. The doses given were 6.6, 11.0, and 15.4 mg/kg. The infusion process lasted for 30 minutes.
• The Vancomycin concentration in the plasma and synovial fluid of these horses was measured using polarization immunoassay, a technique used to quantify the amount of a substance in a solution.
• A pharmacokinetic model was developed to accommodate the particular aspects of this study.

Pharmacokinetic Model

• The data was analyzed using a two-compartment open model, wherein the synovial fluid was considered an additional compartment exchanging with plasma.
• This model describes how the drug is absorbed, distributed, metabolized, and excreted, providing a theoretical framework that reflects the process of drug treatment in horses.

Minimum Inhibitory Concentration (MIC) and Minimum Bacterial Concentration (MBC)

• The MIC and MBC were determined for two bacteria: Staphylococcus aureus and Enterococcus species. These two were chosen because they are common in hospital settings and are typically resistant to many antibiotics.
• The use of clinical isolates from hospital patients helps to accurately represent potential real-world infections in the MIC and MBC testing.
• The MIC is the lowest concentration of an antimicrobial that can inhibit the visible growth of a microorganism, and the MBC is the lowest concentration of an antimicrobial that results in microbial death.

Establishing a Therapeutic Protocol

• Basing on the results of the pharmacokinetic model and the MIC/MBC data, a practical therapeutic protocol was developed for administering Vancomycin in horses.
• This protocol prescribed doses of 4.3-7.5 mg/kg to be given as a 1-hour infusion every 8 hours to ensure effectiveness and safety of the drug in horses.